Rapid Formation of Uniform Cracks in Metal-Assisted Etched Silicon Nanowire Array Membranes: Implications for Transfer of Nanowires and Flexible Devices

Horizontal cracks in the metal-assisted etched SiNW array membrane significantly facilitate the uniform transfer of silicon nanowire (SiNW) array onto foreign substrates. Herein, for the first time, we elucidate that the oxidative dissolution of silver by dissolved oxygen in hot water is essential to trigger crack formation in silver-assisted etched SiNW array and devise a general strategy for rapidly generating horizontal cracks in metal-assisted etched silicon nanowire array membranes by metal etchants, enabling rapid metal dissolution, spontaneous metal reformation, and subsequent metal-assisted etching of silicon. The rapid metal dissolution by wet metal etchants enables the soaking process to be reduced to 1 min or less at room temperature. We anticipate that the present work provides a scientific guidance to prepare a cracked SiNW array membrane in terms of simplicity and scalability and paves the way for mass production of SiNW-based flexible devices such as solar cells, sensors, and batteries.